JP3643693B2 - Manufacturing method of sealed battery - Google Patents

Manufacturing method of sealed battery Download PDF

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Publication number
JP3643693B2
JP3643693B2 JP08580898A JP8580898A JP3643693B2 JP 3643693 B2 JP3643693 B2 JP 3643693B2 JP 08580898 A JP08580898 A JP 08580898A JP 8580898 A JP8580898 A JP 8580898A JP 3643693 B2 JP3643693 B2 JP 3643693B2
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Japan
Prior art keywords
explosion
battery
proof valve
welded
valve
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JP08580898A
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Japanese (ja)
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JPH11283598A (en
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拓磨 森下
雅統 大木
章 黒田
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Sanyo Electric Co Ltd
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Sanyo Electric Co Ltd
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

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  • Secondary Cells (AREA)
  • Gas Exhaust Devices For Batteries (AREA)

Description

【0001】
【発明の属する技術分野】
本発明は、内部に発電要素が収納された有底筒状の外装缶と、この外装缶の開口部を封口する封口体とを有し、この封口体の一部を構成する弁キャップと、上記封口体の内部に存在すると共に電池内圧が異常に上昇した際に上記発電要素と外部端子との接触を絶ってそれ以上の充電を中止させる防爆弁とが共にアルミニウム材料から成り、且つ上記弁キャップと上記防爆弁とが直接的に或いはアルミニウム材料から成る金属箔を介して抵抗溶接法にて溶接される密閉型電池の製造方法に関する。
【0002】
【従来の技術】
近年、携帯電話等の電子機器には非水電解質電池が用いられるようになってきたが、この場合、電池の重量エネルギー密度の向上等を図るべく、比重の小さなアルミニウム又はアルミニウム合金(以下、アルミニウム材料と総称する)が電池材料として用いられるようになってきた。
このため、封口体の一部を構成する弁キャップ、及び封口体の内部に存在すると共に電池内圧が異常に上昇した際に上記発電要素と外部端子との接触を絶ってそれ以上の充電を中止させる防爆弁等についてもアルミニウム材料から構成されるようになってきた。
【0003】
ところで、上記防爆弁は上記弁キャップと直接的に或いはアルミニウム材料から成る金属箔(以下、弁キャップ及び金属箔を弁キャップ等と総称する)を介して溶接されるのであるが、この際、超音波溶接法又はレーザー溶接法を用いると電池の製造コストが高くなり、しかも超音波溶接法を用いた場合には、溶接可能な範囲が狭くて溶接条件の設定が困難であり、しかも過剰に加圧されたり過剰な振動エネルギーを加えられたりすることにより被溶接材料にクラックが発生する等の課題を有していた。
【0004】
そこで、上記のような問題を生じない抵抗溶接法により、上記防爆弁と上記弁キャップ等とを溶接するようなことも考えられる。しかしながら、アルミニウム材料は抵抗が小さいため、低電流では溶接することができない一方、高電流で溶接すると爆火、ピンホールの発生又は電極棒へのアルミニウム材料の付着或いは磨耗等の課題が生じるため、アルミニウム材料同士を抵抗溶接法にて溶接するのは困難であるという課題を有していた。
【0005】
【発明が解決しようとする課題】
本発明は、以上の事情に鑑みなされたものであって、防爆弁と弁キャップ等とを抵抗溶接法にて確実に溶接できることにより、製造コストの低減と電池の信頼性の向上とを図ることができる密閉型電池の製造方法の提供を目的とする。
【0006】
【課題を解決するための手段】
上記目的を達成するための第1の態様の発明は、内部に発電要素が収納された有底筒状の外装缶と、この外装缶の開口部を封口する封口体とを有し、この封口体の一部を構成する弁キャップと、上記封口体の内部に存在すると共に電池内圧が異常に上昇した際に上記発電要素と外部端子との接触を絶ってそれ以上の充電を中止させる防爆弁とが共にアルミニウム材料から成り、且つ上記弁キャップと上記防爆弁とが直接的に或いはアルミニウム材料から成る金属箔を介して抵抗溶接法にて溶接される密閉型電池の製造方法であって、上記抵抗溶接法に用いられる電極棒と上記防爆弁との間に、アルミニウム材料よりも固有抵抗が高くて導電性を有する金属片が介在された状態で抵抗溶接されることを特徴とする。
【0007】
上記構成の如く、電極棒と防爆弁との間にアルミニウム材料よりも固有抵抗が高くて導電性を有する金属片が介在された状態で抵抗溶接すれば、金属片はアルミニウム材料よりも固有抵抗が高いことに起因して、低電流でエネルギーが発生することになる。そして、このエネルギーは防爆弁を介して防爆弁と弁キャップ等との界面に伝播され、これにより両者が溶接されることになる。このように、電極棒とアルミニウム材料から成る防爆弁とが直接接触しない状態で、しかも低電流で両者を溶接することができるので、爆火、ピンホールの発生又は電極棒へのアルミニウム材料の付着或いは磨耗等の問題を生じることなく溶接することができる。
【0008】
また、第2の態様の発明は、上記第1の態様の発明において、上記金属片が、上記電極棒とは同一材質ではない材質から成ることを特徴とする。このような構成であれば、金属片と電極棒とが溶着することがないので、一層円滑に抵抗溶接を行うことができる。
【0009】
また、第3の態様の発明は、上記第1又は2の態様の発明において、上記金属片がアルミニウム材料より融点が高いものから成ることを特徴とする。このように、金属片がアルミニウム材料より融点が高ければ、金属片が防爆弁に溶接されるのを抑制することができる。したがって、電池重量の増大を招くことが無いので、電池のエネルギー密度の低下を防止できる。
また、上記第4の態様の発明は、上記第3の態様の発明において、上記金属片がニッケル又は鉄から成ることを特徴とする。
【0010】
【発明の実施の形態】
本発明の実施の形態を、図1〜図3に基づいて、以下に説明する。
図1は本発明に係るリチウムイオン電池の分解斜視図、図2は電池の封口体の拡大半断面図、図3は溶接時の状態を示す拡大断面図である。
【0011】
図1に示すように、本発明のリチウムイオン電池は、有底円筒状の外装缶5を有しており、この外装缶5内には、アルミニウムから成る芯体にLiCoO2 を主体とする活物質層が形成された正極1と、銅から成る芯体に黒鉛を主体とする活物質層が形成された負極2と、これら両電極1・2を離間するセパレータ3とから成る渦巻き状の発電要素4が収納されている。また、上記外装缶5内には、エチレンカーボネート(EC)とジメチルカーボネート(DMC)とが体積比で4:6の割合で混合された混合溶媒に、LiPF6 が1M(モル/リットル)の割合で溶解された電解液が注入されている。更に、上記外装缶5の開口部には封口体6がかしめ固定されており、これによって電池が封口される。
【0012】
ここで、上記封口体6は、図2に示すように、アルミニウム合金から成り且つガス抜き穴23を有する弁キャップ9を有している。この弁キャップ9上には、アルミニウム合金から成ると共に両端が弁キャップ9に溶接された金属箔11が設けられており、この金属箔11上には、アルミニウム合金から成ると共に略半円球状を成す防爆弁8が溶接されている。この防爆弁8は、封口体内部20と電池本体部21とを区切るものであり、通常状態では、弁キャップ9を介して正極集電タブ10と電気的に接続された金属箔11と溶接されている一方(図中、実線で示す)、過充電時等の異常時に電池内部の圧力が所定値(10〜20kgf/cm2 )以上になった場合には、金属箔11から剥がれて、これにより充電が中止される(図中、二点鎖線で示す)。また、上記防爆弁8の端部上には、順に、PTC素子12と、ガス抜き穴24が設けられた正極端子7とが設けられている。また、前記弁キャップ9はポリプロピレン(PP)から成る絶縁性の外部ガスケット14を介して前記外装缶5にかしめ固定されて、これにより電池内部が封止される一方、上記防爆弁9、上記PTC素子12、及び上記正極端子7はPPから成る絶縁性の内部ガスケット15を介して弁キャップ9にかしめ固定されて、これにより封口体内部20が封止される。
【0013】
更に、前記外装缶5には、負極2と電気的に接続された負極集電タブ13が接続され、且つ前記発電要素4の上下両端部近傍には、絶縁板16・17が配置されている。
【0014】
ここで、上記構造の非水電解質電池を、以下のようにして作製した。
先ず、正極活物質としてのLiCoO2 を90重量%と、導電剤としてのカーボンブラックを5重量%と、結着剤としてのポリフッ化ビニリデンを5重量%と、溶剤としてのN−メチル−2−ピロリドン(NMP)溶液とを混合してスラリーを調製した後、正極集電タブ10の溶接部位を除き、上記スラリーを正極集電体としてのアルミニウム箔(厚み:20μm)の両面に塗布した。その後、溶剤を乾燥し、ローラーで所定の厚みにまで圧縮した後、所定の幅及び長さになるように切断し、更にアルミニウム製の正極集電タブ10(幅:3mm)を溶接した。
【0015】
これと並行して、負極活物質としての黒鉛粉末を95重量%と、結着剤としてのポリフッ化ビニリデンを5重量%と、溶剤としてのNMP溶液とを混合してスラリーを調製した後、負極集電タブ13の溶接部位を除き、上記スラリーを負極集電体としての銅箔(厚み:16μm)の両面に塗布した。その後、溶剤を乾燥し、ローラーで所定の厚みにまで圧縮した後、所定の幅及び長さになるように切断し、更にニッケル製の負極集電タブ13(幅:3mm)を溶接した。
【0016】
次に、上記正極1と負極2とをポリエチレン製微多孔膜から成るセパレータ3(厚み:25μm)を介して巻回して発電要素4を作製した後、この発電要素4を絶縁板16と共に外装缶5内に挿入し、更に負極集電タブ13を外装缶5の缶底に溶接した。
その後、図3に示すように、先ず、弁キャップ9上に金属箔11を載置し、金属箔11の両端(図中A1、A2で示す)を、レーザー溶接法を用いて弁キャップに溶接した。次に、一方の電極を兼ねる基台22上に、金属箔11が溶接された弁キャップ9を載置し、更に金属箔11の表面に防爆弁8とニッケルから成る金属片24(厚み:0.1mm)とを順に載置した。次いで、他方の電極となる電極棒23の先端部を上記金属片24に当接し、更に電流を流すことにより、金属箔11と防爆弁8とを抵抗溶接(図中Bで示す)した後、電極棒23と金属片24とを外した。
【0017】
尚、上記抵抗溶接における溶接条件は、圧力1〜5kg、電流値0.5〜2kAの範囲で行うのが望ましい。なぜなら、余り低い圧力及び電流値で抵抗溶接を行うと十分な溶接強度が得られない一方、余り高い圧力及び電流値で抵抗溶接を行うと爆火等の問題が生じるからである。
【0018】
しかる後、正極集電タブ10を封口板6に溶接すると共に、ECとDMCとが体積比で4:6の割合で混合された混合溶媒に、LiPF6 が1M(モル/リットル)の割合で溶解された電解液を外装缶5内に注入した後、封口板6を外装缶5の開口端部にかしめ固定することにより、円筒形の電池を作製した。
【0019】
尚、上記実施の形態では、防爆弁8と金属箔11とのみが溶接され、金属片24と防爆弁8とは溶接されていないが、防爆弁8と金属箔11とを溶接すると共に金属片24と防爆弁8とを溶接するようにしても良い。但し、金属片24と防爆弁8とを溶接すれば、金属片24の重量分だけ電池重量も増大する。したがって、電池の重量エネルギー密度という観点からは金属片24と防爆弁8とを溶接しないのが望ましい。
【0020】
また、防爆弁8と弁キャップ9との間に金属箔11を設けるような構造に限定するものではなく、防爆弁8と弁キャップ9とを抵抗溶接法にて直接溶接するようにしても良い。
更に、金属片24の厚みは0.1mmに限定するものではなく、0.05〜0.5mmであれば良く、特に、溶接部にエネルギーを円滑に伝達するためには0.05〜0.15mmの範囲であるのが望ましい。
【0021】
加えて、防爆弁8、弁キャップ9、及び金属箔11はアルミニウム合金に限定するものではなく金属アルミニウムを用いても良く、また本発明は上記リチウムイオン電池に限定するものではなく、防爆弁8、弁キャップ9等にアルミニウム材料を用いた電池であれば適用しうることは勿論である。
但し、本発明を上記リチウムイオン電池に適用する場合には、正極材料としては上記LiCoO2 の他、例えば、LiNiO2 、LiMn2 4 或いはこれらの複合体等が好適に用いられ、また負極材料としては上記炭素材料の他、リチウム金属、リチウム合金、或いは金属酸化物(スズ酸化物等)等が好適に用いられる。更に、電解液の溶媒としては上記のものに限らず、プロピレンカーボネート、エチレンカーボネート、ビニレンカーボネート、γ−ブチロラクトンなどの比較的比誘電率が高い溶液と、ジエチルカーボネート、ジメチルカーボネート、メチルエチルカーボネート、テトラヒドロフラン、1,2−ジメトキシエタン、1,3−ジオキソラン、2−メトキシテトラヒドロフラン、ジエチルエーテル等の低粘度低沸点溶媒とを適度な比率で混合した溶媒を用いることができる。また、電解液の電解質としては、上記LiPF6 の他、LiAsF6 、LiClO4 、LiBF4 、LiCF3 SO3 等を用いることができる。
【0022】
【実施例】
〔実施例1〕
実施例1としては、上記発明の実施の形態に示す方法と同様の方法にて作製した電池を用いた。
このようにして作製した電池を、以下、本発明電池A1と称する。
〔実施例2〕
金属片24がニッケルではなく鉄から成るものを用いて電池を作製する他は、上記実施例1と同様にして電池を作製した。
このようにして作製した電池を、以下、本発明電池A2と称する。
【0023】
〔比較例1〕
金属片24を防爆弁8上に載置することなく電池を作製する他は、上記実施例1と同様にして電池を作製した。
このようにして作製した電池を、以下、比較電池X1と称する。
〔比較例2〕
金属片24を防爆弁8上に載置することなく、且つ 金属箔11と防爆弁8とをレーザー溶接法にて溶接する他は上記実施例1と同様にして電池を作製した。
このようにして作製した電池を、以下、比較電池X2と称する。
【0024】
〔実験〕
上記本発明電池A1、A2及び比較電池X1、X2について、溶接不良数とリーク数とについて調べたので、その結果を下記表1に示す。
【0025】
【表1】

Figure 0003643693
【0026】
上記表1から明らかなように、比較電池X1、X2では溶接不良と電池のリークとが生じているのに対して、本発明電池A1、A2では溶接不良と電池のリークとが全く生じていないことが認められる。
したがって、アルミニウム材料同士を溶接する際に、アルミニウム材料より固有抵抗が高い金属片24を介することなく両者を抵抗溶接法にて溶接したり、またレーザー溶接法にて両者を溶接するのは好ましくなく、金属片24を介して両者を抵抗溶接法にて溶接するのが好ましことがわかる。
【0027】
【発明の効果】
以上説明したように、本発明によれば、防爆弁と弁キャップ等とを抵抗溶接法にて確実に溶接できることにより、製造コストの低減と電池の信頼性の向上とを図ることができるといった優れた効果を奏する。
【図面の簡単な説明】
【図1】図1は本発明に係るリチウムイオン電池の分解斜視図である。
【図2】図2は電池の封口体の拡大半断面図である。
【図3】図3は溶接時の状態を示す拡大断面図である。
【符号の説明】
4:発電要素
5:外装缶
6:封口体
7:正極端子
8:防爆弁
9:弁キャップ
11:金属箔
23:電極棒
24:金属片[0001]
BACKGROUND OF THE INVENTION
The present invention has a bottomed cylindrical outer can in which a power generation element is housed inside, a sealing body that seals the opening of the outer can, and a valve cap that constitutes a part of the sealing body; An explosion-proof valve that exists inside the sealing body and that stops contact with the power generating element and external terminals when the internal pressure of the battery abnormally increases is made of an aluminum material, and the valve The present invention relates to a method of manufacturing a sealed battery in which a cap and the explosion-proof valve are welded by resistance welding directly or through a metal foil made of an aluminum material.
[0002]
[Prior art]
In recent years, non-aqueous electrolyte batteries have come to be used for electronic devices such as mobile phones. In this case, in order to improve the weight energy density of the batteries, aluminum or an aluminum alloy (hereinafter referred to as aluminum) having a small specific gravity. Have been used as battery materials.
For this reason, the valve cap that constitutes a part of the sealing body, and when the internal pressure of the battery rises abnormally when the internal pressure of the battery rises abnormally, the contact between the power generation element and the external terminal is cut off and further charging is stopped. Explosion-proof valves and the like that have been made are made of aluminum materials.
[0003]
By the way, the explosion-proof valve is welded to the valve cap directly or via a metal foil made of an aluminum material (hereinafter, the valve cap and the metal foil are collectively referred to as a valve cap or the like). If the ultrasonic welding method or laser welding method is used, the manufacturing cost of the battery increases, and if the ultrasonic welding method is used, it is difficult to set the welding conditions because the weldable range is narrow, and excessive addition is required. There has been a problem that cracks are generated in the material to be welded by being pressed or applying excessive vibration energy.
[0004]
Therefore, it is conceivable to weld the explosion-proof valve and the valve cap or the like by a resistance welding method that does not cause the above problems. However, since the aluminum material has low resistance, it cannot be welded at a low current. On the other hand, welding at a high current causes problems such as explosion, generation of pinholes, or adhesion or wear of the aluminum material to the electrode rod. It had the subject that it was difficult to weld aluminum materials with a resistance welding method.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and is capable of reliably welding an explosion-proof valve and a valve cap by a resistance welding method, thereby reducing manufacturing cost and improving battery reliability. It is an object of the present invention to provide a method for producing a sealed battery that can be used.
[0006]
[Means for Solving the Problems]
The invention of the first aspect for achieving the above object has a bottomed cylindrical outer can in which a power generation element is housed, and a sealing body for sealing an opening of the outer can. A valve cap that constitutes a part of the body, and an explosion-proof valve that exists inside the sealing body and that stops contact with the power generation element and external terminals when battery internal pressure rises abnormally and stops further charging Are both made of an aluminum material, and the valve cap and the explosion-proof valve are welded by resistance welding directly or through a metal foil made of an aluminum material. It is characterized in that resistance welding is performed in a state in which a metal piece having higher resistivity and conductivity than an aluminum material is interposed between an electrode rod used in resistance welding and the explosion-proof valve.
[0007]
As in the above configuration, if resistance welding is performed in a state where a metal piece having a higher resistivity than an aluminum material and having conductivity is interposed between the electrode rod and the explosion-proof valve, the metal piece has a resistivity higher than that of the aluminum material. Due to the high, energy is generated at a low current. This energy is transmitted to the interface between the explosion-proof valve and the valve cap through the explosion-proof valve, and both are welded. In this way, since the electrode rod and the explosion-proof valve made of aluminum material are not in direct contact with each other and can be welded at a low current, an explosion, generation of a pinhole or adhesion of the aluminum material to the electrode rod is possible. Alternatively, welding can be performed without causing problems such as wear.
[0008]
According to a second aspect of the present invention, in the first aspect of the invention, the metal piece is made of a material that is not the same material as the electrode rod. With such a configuration, resistance welding can be performed more smoothly because the metal piece and the electrode rod are not welded.
[0009]
According to a third aspect of the present invention, in the first or second aspect of the invention, the metal piece is made of a material having a melting point higher than that of the aluminum material. Thus, the metal strip is higher melting point than an aluminum material, it is possible to prevent the metal piece is welded to the explosion-proof valve. Therefore, since the increase in battery weight is not caused, a decrease in the energy density of the battery can be prevented.
The invention of the fourth aspect is characterized in that, in the invention of the third aspect , the metal piece is made of nickel or iron.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS.
FIG. 1 is an exploded perspective view of a lithium ion battery according to the present invention, FIG. 2 is an enlarged half sectional view of a battery sealing body, and FIG. 3 is an enlarged sectional view showing a state during welding.
[0011]
As shown in FIG. 1, the lithium ion battery of the present invention has a bottomed cylindrical outer can 5, and in the outer can 5, an active core mainly composed of LiCoO 2 is formed of an aluminum core. Spiral power generation comprising a positive electrode 1 with a material layer, a negative electrode 2 with an active material layer mainly composed of graphite formed on a copper core, and a separator 3 that separates the electrodes 1 and 2 Element 4 is housed. Further, in the outer can 5, a ratio of 1 M (mol / liter) of LiPF 6 to a mixed solvent in which ethylene carbonate (EC) and dimethyl carbonate (DMC) are mixed at a volume ratio of 4: 6. The electrolytic solution dissolved in is injected. Further, a sealing body 6 is caulked and fixed to the opening of the outer can 5, thereby sealing the battery.
[0012]
Here, the sealing body 6 has a valve cap 9 made of an aluminum alloy and having a vent hole 23 as shown in FIG. A metal foil 11 made of an aluminum alloy and welded at both ends to the valve cap 9 is provided on the valve cap 9. The metal foil 11 is made of an aluminum alloy and has a substantially hemispherical shape. The explosion-proof valve 8 is welded. The explosion-proof valve 8 separates the sealing body interior 20 from the battery body 21 and is welded to the metal foil 11 electrically connected to the positive electrode current collecting tab 10 through the valve cap 9 in a normal state. On the other hand (indicated by a solid line in the figure), when the internal pressure of the battery exceeds a predetermined value (10 to 20 kgf / cm 2 ) at the time of abnormality such as overcharge, the metal foil 11 is peeled off. To stop charging (indicated by a two-dot chain line in the figure). Further, on the end portion of the explosion-proof valve 8, a PTC element 12 and a positive electrode terminal 7 provided with a gas vent hole 24 are provided in this order. The valve cap 9 is caulked and fixed to the outer can 5 via an insulating external gasket 14 made of polypropylene (PP), thereby sealing the inside of the battery, while the explosion-proof valve 9 and the PTC. The element 12 and the positive electrode terminal 7 are caulked and fixed to the valve cap 9 via an insulating internal gasket 15 made of PP, thereby sealing the inside 20 of the sealing body.
[0013]
Further, a negative electrode current collecting tab 13 electrically connected to the negative electrode 2 is connected to the outer can 5, and insulating plates 16 and 17 are disposed in the vicinity of both upper and lower ends of the power generating element 4. .
[0014]
Here, the non-aqueous electrolyte battery having the above structure was produced as follows.
First, 90% by weight of LiCoO 2 as a positive electrode active material, 5% by weight of carbon black as a conductive agent, 5% by weight of polyvinylidene fluoride as a binder, and N-methyl-2- 2 as a solvent. After preparing a slurry by mixing with a pyrrolidone (NMP) solution, the above-mentioned slurry was applied to both surfaces of an aluminum foil (thickness: 20 μm) as a positive electrode current collector, except for the welded portion of the positive electrode current collector tab 10. Then, after drying the solvent and compressing to a predetermined thickness with a roller, it was cut so as to have a predetermined width and length, and an aluminum positive electrode current collecting tab 10 (width: 3 mm) was welded.
[0015]
In parallel with this, a slurry was prepared by mixing 95% by weight of graphite powder as a negative electrode active material, 5% by weight of polyvinylidene fluoride as a binder, and an NMP solution as a solvent. The slurry was applied to both sides of a copper foil (thickness: 16 μm) as a negative electrode current collector, except for the welded portion of the current collecting tab 13. Thereafter, the solvent was dried, compressed to a predetermined thickness with a roller, cut to a predetermined width and length, and further, a nickel negative electrode current collecting tab 13 (width: 3 mm) was welded.
[0016]
Next, after the positive electrode 1 and the negative electrode 2 are wound through a separator 3 (thickness: 25 μm) made of a polyethylene microporous film, a power generation element 4 is produced. The negative electrode current collecting tab 13 was further welded to the bottom of the outer can 5.
Thereafter, as shown in FIG. 3, first, the metal foil 11 is placed on the valve cap 9, and both ends (indicated by A1 and A2 in the figure) of the metal foil 11 are welded to the valve cap using a laser welding method. did. Next, the valve cap 9 to which the metal foil 11 is welded is placed on the base 22 also serving as one electrode, and the explosion-proof valve 8 and a metal piece 24 (thickness: 0) made of nickel are further formed on the surface of the metal foil 11. .1 mm). Next, the metal foil 11 and the explosion-proof valve 8 are resistance-welded (indicated by B in the figure) by bringing the tip of the electrode rod 23 to be the other electrode into contact with the metal piece 24 and further flowing an electric current, The electrode rod 23 and the metal piece 24 were removed.
[0017]
In addition, it is desirable to perform the welding conditions in the said resistance welding in the range of a pressure of 1-5 kg and the electric current value of 0.5-2 kA. This is because sufficient welding strength cannot be obtained when resistance welding is performed at a very low pressure and current value, while problems such as explosions occur when resistance welding is performed at a too high pressure and current value.
[0018]
Thereafter, the positive electrode current collecting tab 10 is welded to the sealing plate 6, and LiPF 6 is mixed at a ratio of 1 M (mol / liter) in a mixed solvent in which EC and DMC are mixed at a volume ratio of 4: 6. After injecting the dissolved electrolyte solution into the outer can 5, the sealing plate 6 was caulked and fixed to the opening end of the outer can 5, thereby producing a cylindrical battery.
[0019]
In the above embodiment, only the explosion-proof valve 8 and the metal foil 11 are welded, and the metal piece 24 and the explosion-proof valve 8 are not welded, but the explosion-proof valve 8 and the metal foil 11 are welded and the metal piece. 24 and the explosion-proof valve 8 may be welded. However, if the metal piece 24 and the explosion-proof valve 8 are welded, the battery weight increases by the weight of the metal piece 24. Therefore, it is desirable not to weld the metal piece 24 and the explosion-proof valve 8 from the viewpoint of the weight energy density of the battery.
[0020]
Further, the present invention is not limited to the structure in which the metal foil 11 is provided between the explosion-proof valve 8 and the valve cap 9, and the explosion-proof valve 8 and the valve cap 9 may be directly welded by resistance welding. .
Further, the thickness of the metal piece 24 is not limited to 0.1 mm, and may be 0.05 to 0.5 mm. In particular, in order to smoothly transmit energy to the welded portion, 0.05 to 0.00 mm. A range of 15 mm is desirable.
[0021]
In addition, the explosion-proof valve 8, the valve cap 9, and the metal foil 11 are not limited to an aluminum alloy, and may use metal aluminum. The present invention is not limited to the lithium ion battery, and the explosion-proof valve 8. Of course, any battery using an aluminum material for the valve cap 9 or the like can be applied.
However, when the present invention is applied to the lithium ion battery, as the positive electrode material, for example, LiNiO 2 , LiMn 2 O 4, or a composite thereof is preferably used in addition to the LiCoO 2 , and the negative electrode material In addition to the above carbon material, lithium metal, lithium alloy, metal oxide (such as tin oxide) or the like is preferably used. Further, the solvent of the electrolytic solution is not limited to the above, but a solution having a relatively high relative dielectric constant such as propylene carbonate, ethylene carbonate, vinylene carbonate, γ-butyrolactone, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, tetrahydrofuran , 1,2-dimethoxyethane, 1,3-dioxolane, 2-methoxytetrahydrofuran, a solvent having a low boiling point such as diethyl ether mixed in an appropriate ratio can be used. In addition to LiPF 6 , LiAsF 6 , LiClO 4 , LiBF 4 , LiCF 3 SO 3, etc. can be used as the electrolyte of the electrolytic solution.
[0022]
【Example】
[Example 1]
As Example 1, a battery manufactured by a method similar to the method described in the embodiment of the present invention was used.
The battery thus produced is hereinafter referred to as the present invention battery A1.
[Example 2]
A battery was manufactured in the same manner as in Example 1 except that the battery was manufactured using a metal piece 24 made of iron instead of nickel.
The battery thus produced is hereinafter referred to as the present invention battery A2.
[0023]
[Comparative Example 1]
A battery was fabricated in the same manner as in Example 1 except that the battery was fabricated without placing the metal piece 24 on the explosion-proof valve 8.
The battery thus produced is hereinafter referred to as comparative battery X1.
[Comparative Example 2]
A battery was fabricated in the same manner as in Example 1 except that the metal piece 24 was not placed on the explosion-proof valve 8 and the metal foil 11 and the explosion-proof valve 8 were welded by laser welding.
The battery thus produced is hereinafter referred to as comparative battery X2.
[0024]
[Experiment]
Since the number of defective welding and the number of leaks were examined for the above-described inventive batteries A1 and A2 and comparative batteries X1 and X2, the results are shown in Table 1 below.
[0025]
[Table 1]
Figure 0003643693
[0026]
As is apparent from Table 1 above, the comparative batteries X1 and X2 have poor welding and battery leakage, whereas the inventive batteries A1 and A2 have no welding failure and battery leakage at all. It is recognized that
Therefore, when welding aluminum materials, it is not preferable to weld the two by resistance welding without using the metal piece 24 having a higher specific resistance than the aluminum material, or by welding by laser welding. It can be seen that it is preferable to weld both of them through a metal piece 24 by resistance welding.
[0027]
【The invention's effect】
As described above, according to the present invention, the explosion-proof valve and the valve cap can be reliably welded by the resistance welding method, so that the manufacturing cost can be reduced and the battery reliability can be improved. Has an effect.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a lithium ion battery according to the present invention.
FIG. 2 is an enlarged half sectional view of a battery sealing body.
FIG. 3 is an enlarged cross-sectional view showing a state during welding.
[Explanation of symbols]
4: Power generation element 5: Exterior can 6: Sealing body 7: Positive electrode terminal 8: Explosion-proof valve 9: Valve cap 11: Metal foil 23: Electrode rod 24: Metal piece

Claims (2)

内部に発電要素が収納された有底筒状の外装缶と、この外装缶の開口部を封口する封口体と、上記封口体の一部を構成する弁キャップと、上記封口体の内部に存在電池内圧が異常に上昇した際に上記発電要素と外部端子との接触を絶ってそれ以上の充電を中止させる防爆弁と、を有し、
上記弁キャップと上記防爆弁とが共にアルミニウム材料から成り直接的に或いはアルミニウム材料から成る金属箔を介して、電極棒を用いた抵抗溶接法にて溶接される密閉型電池の製造方法であって、
上記抵抗溶接法が、上記電極棒と上記防爆弁との間に、アルミニウム材料よりも融点と固有抵抗が高く、且つ上記電極棒と同一材質でない、導電性を有する金属片を介在させた状態で抵抗溶接する方法であることを特徴とする密閉型電池の製造方法。
A bottomed cylindrical outer can power generating element therein is accommodated, and a sealing body for sealing the opening of the outer can, a valve cap constituting a part of the sealing body, present inside the sealing member And an explosion-proof valve that stops contact with the power generation element and the external terminal when the battery internal pressure rises abnormally, and stops further charging .
Made from the valve cap and the explosion-proof valve are both aluminum material, there by directly or via a metal foil made of aluminum material, manufacturing method of sealed battery that is welded by resistance welding method using an electrode rod And
In the state where the resistance welding method has a conductive metal piece having a melting point and a specific resistance higher than those of an aluminum material and not the same material as the electrode rod, between the electrode rod and the explosion-proof valve. A method for producing a sealed battery, which is a resistance welding method.
上記金属片はニッケル又は鉄から成る、請求項1記載の密閉型電池の製造方法。The method for manufacturing a sealed battery according to claim 1 , wherein the metal piece is made of nickel or iron.
JP08580898A 1998-03-31 1998-03-31 Manufacturing method of sealed battery Expired - Fee Related JP3643693B2 (en)

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JP2014132516A (en) * 2011-04-28 2014-07-17 Hitachi Maxell Ltd Cylindrical lithium ion secondary battery and method of manufacturing the same
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CN113659256A (en) * 2021-07-21 2021-11-16 广州市金特电子科技有限公司 Battery cap structure and lithium battery structure

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